The present disclosure relates to a power transmission apparatus including a transmission, a case that accommodates the transmission, a counter drive gear to which power from the transmission is transmitted, and a counter driven gear that meshes with the counter drive gear.
Conventionally for this type of power transmission apparatus, a power transmission apparatus is known that includes a speed change mechanism having a multi-plate friction type brake capable of fixing a sun gear of a speed reducing planetary gear to a transmission case so that the sun gear is not rotatable, a counter drive gear to which power from the speed change mechanism is transmitted, a counter driven gear that meshes with the counter drive gear, a drive pinion gear integrated with a countershaft and fitted through a spline to the counter driven gear, and a center support that is fastened to the transmission case with a bolt and that supports the counter drive gear so that the counter drive gear is rotatable (see e.g., JP 2002-349683 A). A brake drum constituting the brake of the power transmission apparatus includes a radial flange portion extending from one end in a radially inward direction. An inner circumferential portion of the radial flange portion has inner circumferential teeth. By fitting the inner circumferential teeth to protrusions formed on a wall surface of an outer circumferential portion of the center support, the brake drum is fixed to the center support so as not to be rotatable. An oil chamber of the brake is defined in an oil pump body that is spaced apart toward a side (engine side) from the brake drum, and return springs that bias a piston disposed in the oil chamber are disposed beside the brake drum (the engine side).